[BEIJING] Chinese scientists have identified and cloned a rice gene that influences rice grain weight and yield, which could help scientists develop higher yielding varieties of the world's most important food crop.

Little is known about the genetic mechanisms that determine yield and seed weight in plants, despite tremendous efforts by agricultural scientists in the past decade.

In a study published this week (8 April) in Nature Genetics, lead author Lin Hongxuan and colleagues from the Shanghai Institutes for Biological Sciences, studied two varieties of rice with highly significant differences in grain size.

After mapping their genomes, they found a gene called GW2 in the large-grain rice that was lacking in the small-grain rice.

They then created a variety of the naturally small-grained rice with the GW2 gene, and found that the gene increased the width and weight of rice grains and increased grain yield per plant by nearly 20 per cent.

The high-yield variant had nearly the same cooking or eating quality as conventional rice, although the grains had a darker appearance.

The team say the GW2 gene will facilitate breeding efforts to improve grain yield in food crops. But they say further evidence is needed to support their finding.

"The increased output of single plants might be influenced by environmental factors, so our finding needs to be tested in the randomised blocks of plants in paddies," Lin told SciDev.Net.

He said the GW2 gene might affect grain size by regulating the cell division cycle.

Zhu Zhen, deputy director of the Bureau of Life Sciences and Biotechnology of the Chinese Academy of Sciences, praised the study, saying it would give breeders more alternatives to explore in the search for improved varieties of rice.

"In the process of developing new crop varieties, the discovery of important agronomical genes is very important," Zhu told SciDev.Net.